Photoelectric convection smoke detector



July 4, 1950 C. N. CAHUSAC ET AL PHOTOELEC'I'RIC VCONVEICTION SMOKE DETECTOR 2 Sheets-Sheet 1 CLHRENCE gz CaHusHc' DONHLD man@ July 4, 1950 c. N. cAHusAc ErAL PHOTOELECTRIC CNVECTION SMOKE DETECTOR 2 Sheets-Sheet 2 Filed Sept. 28, 1946 zveaf.' CLHRENCE NOEL CaHusac,

Patented `Iuly 4, 1950 'PHOTOELECTRIC CONVIECTION SMKE DETECTGR;V

clarence Noel cahusac, Newark, ana' Donald A; Diehl, Arlington, N. J., assigners to C-O-Two- Fire Equipment Co.,` Newark; N. JL, aE corporaf tion of Delaware Application september 2s, 1946, serial'No. 700,052

(o1. 250g-21's) 5Claims. 11

This invention relates in general toapparatus for detecting and announcing` the existenceat a` polni-I remote from the apparatus-ofi a iluid having particles of matter suspended therein such as smoke; more particularly, the invention contemplates such apparatus which isespecially adapted-fori detecting the presence* ofL smoke in the various compartmentsor roomsof airplanes,- ships; railwaycars, and buildings,A and producing asignal, for example, ontheinstrument board ofI an-airplane, to ensureL immediate warning oi res and=prompt action toextinguish them.

The inventionn especiallycontemplatesy smoke detectorsof the type whereinY the detector unitI islocated in the space being protectedandsmoke'- from'such space is conducted `through the casing ofthe detector in which is locatedY apparatus responsiveto the presence of,` the smoke, for example, smoke detectors which include means for producing a beam of light, means for conduct- 1 ing* a stream of smoke int'ofsaid beam, andv al photoelectric element located tobe permanently illuminated`` by said light beam* so that whenl fluidshaving particles Yof matter suspendedv therein passesthrough-said light beam the illumination.y

ofi thephotoelectric elementlisr'weakened. The' photoelectric elementisiconnected in an electric' circuit with another photoelectric element and` an electrical responsive rdevice whereby. the vphotoelectric effectsof: the second-mentioned element opposes ythe photoelectric eiects of the rstmentioned element so `thatsaid electrical responsive device is actuated, for example, to producedl ali-audible or visible signal when smoke is present inthe IightLbeam.`

. Api-imc object ozfy thev presentinvention istoprovide alsmoke detector of the character described whereinl thev smoke shall be caused to. Ilow directly from the protected space through the casing of the detector by thermal circulation,v

ing, a light source, a photoelectric element andv rneans for protectingthe photoelectric element against the effects or lightoutside of the casing; andtb obtain other advantages andresults that will be brought out bythe following description in conjunction With'theiaccompanying drawingsy in whichz' l Figure l isa schematic View, with portions shownin side elevation and otheriportions shownI in Vertical longitudinal section; of theiapparatus embodyingour invention;

andthe provision of a novel and improvedmeans for permitting free iiow of the smoke through the casing and at the same time preventing entry of-light` from outside the casing into the casing,y

Figure Zisa tramsv'e'rsev verticalsectional View Figure 3is a similar View on theplane off the line 3'-3` of Figure 1';

Figure 4' isa'transverse vertical sectional viewv ontle line'lli-d of' Figure 1; l

Figure 5 is a'viewsmilartoFigurel showing a modillcation of the invention;

Figure 6 is a'fragmcntaryview similar to Figure 4; showing aniodlcation.

Figure lis a` fragmentaryvertical longitudinal' sectionalview showing' a modification of the in-f vention; and

Figure 8 is awiring. dlagram'of the detecting and signalingciicuit;

Specically describing. the embodiment ofthe invention illustrated" in'- Figures 1 to 4 inclusive,

the reference character Af generally designates* the casing' of'. the smoke-"detecting unit which l includsa' compartiment4v l which is mounted' a light source 2s'uch as` an incandescent lamp.

One wallo'fthe'compartment' I has an opening 3 y from the lampi?" ar'edirected through a tubular and'pre'f'era'bly cylindricaltesting compartment 5, so' that said rays (represented by broken lines) are projected in' a" parallel beamthrough said compartment.

At theendof thev compartment 5, opposite theV lens system 4'; andl in alignment therewith, is' mounted a photoelectric element 6; upon the liglitsen'sitive surface ofiwhch the beamof'light is permanently directed'cluring operation'oi theY l apparatusi, This photoelectricv element may be of'any suitable type; suclias vtliecurrent generatel ingbarrier layer type,A and preferably has a large flat light-sensitive surfaceil and is capable of` generating sumcient currentto operate an elec-y trical responsive device without amplication of the electrical output of the element.

In use, the casing and compartment 5 are mounted in any suitable manner in the space to be protected, and the compartment 5 is provided with a plurality of apertures8 spaced longitudinally thereof to permit uid, containing suspended matter such as smoke, to pass through the compartment by thermal circulation. The heat produced by the radiant energy of the light beam as well as the heat transmitted through the walls of the smoke detecting compartment from the light source heats the iiuid in the detecting compartment causing the thermal circulation therethrough. It will be observed that as smoke passes through the compartment, it will cross the path of the light rays that are projected from the source 2 to the photoelectric element and thereby partially block the light rays and weaken the illumination of the photoelectric element.

The photoelectric element 6 is Aconnected in an electrical circuit with an electric responsive device 9 and another photoelectric element II) which is subject to rays from the light source 2, said photoelectric elements being connected in the the circuit in what is known as an opposed parallel arrangement, or so that the photoelectric eects of said elements are :caused to operate in compensating differential or opposed relation; in other words, the electrodes of the element 'I are connected respectively to the opposite electrodes of the element I9 Vas best shown in Figure 8.

The photoelectric element I may be mounted in any suitable manner, but as shown, the light compartment I has an aperture in its wall which is -disposed at one end of ya light-conducting tube I2 that projects from said wall of the compartment I and in which the photoelectric element Il) is mounted in spaced and aligned relation to the aperture II. The tube I2 being preferably positionedon,thenopposite side of the compartment I from the lensy system 2.

Within the aperture is mounted suitable means for varying the effect of the light rays upon the photoelectric element Ill.` Such means may comprise, alternatively, an adjustable iris diaphragm |3a, (Figure 6),` or light-diiusing media such as wire gauze I3, (Figure 4), frosted glass or Polaroid glass |3b (Figure 7).

With this construction, initially the photoelectric cell circuit is sov adjusted that the relay or other device 9 will assume a normal condition, for example, to open the signal circuit vwhen no smoke is present in the compartment 6, and when smoke is caused to'flow through the compartment 5 into the beam of light, some of the light rays will be blocked and the illumination of the photoelectric element 6 will be weakened, whereupon the relay or other electrical responsive device 9 will be actuated into the closed position by the current in the photoelectric cell circuit so as to close the signal circuit.

To protect the photoelectric element 6 against the elects of stray light rays from outside the compartment 5, in other words, to prevent the passage of light rays through the apertures 8 in such a manner as to energize'the photoelectric element 6, we provide a plurality of bailles or partitions I4 which extend transversely of the compartment 5 between the apertures 8, and have aligned central openings I5 through which the light beam may freely pass.

With this construction, it will be observed that it is impossible for light raysI to enter the Vcomventing light rays from outside the compartment in any way aiecting the operation of the photoelectric system.

A modication of the invention is shown in Figure 5, where instead of the baffles or partitions I, we utilize inwardly projecting tubes I6, one for each of the apertures I1 corresponding to the apertures 8, said tubes projecting into the testing compartment I8 which corresponds to the compartment 5, a sufficient distance to prevent exterior light rays from entering the compartment in such a way as to vary or otherwise aiect the operation of the photoelectric element.

Thevarious electrical responsive devices may be utilized and they may be connected in circuit in any suitable manner with various 'devices suchv as signal lamps, bells and the like, but one preferred circuit is shown in Figure 8 Where the electrical responsive device 9 includes a pointer or swingablecontact arm I9 which is actuated by a coil 20 connected in circuit with the photoelectric elements so that said pointer is normally spaced from a fixed contact 2|, but is actuated into engagement with said contact when the output of the `photoelectric cells II) and becomev unbalanced, such as by the partial or total de-energizing of either of the cells while the other is energized. Generally, the pointer tends to remain in such contact, yet it is customary to provide means for resetting this contact arm from any desired remote point. For the purpose of illustration, we vhave shown a resetting rod 22 havingv one end normally in spaced relation to the contact arm. I9 when the latter engages the Contact` 2| as. shown in Figure 6, The resetting rod'22 may be electrically operated as hereinafter de,-

scribed. The electrical responsive device 9 e011-, trolsthe signal circuit through contact of said contact arm I9 and contact member 2| in order to complete the circuit 2 any desired electrically operated device, such asa signal lamp 23 which, maybe mounted in any suitable location, for ,ex-z

ample on a remote control board 24 as shown in Figure 8.

In accordance with one feature of .the inven- 1 tion, we provide a switch mechanism operated by the same finger piece for resetting the contact arm I9 of the electrical responsive device .and

testing the apparatus to ascertain whether or not the' photoelectric-elements and the circuit are in operative condition. As shown, an electromagnetic coil 25 is provided for actuating the reset-- ting rod 22 and is connected in circuit with a normally open switch which includes a fixed con-I tact member 26 and a movable contact member 2l that is mounted on a spring arm 28 which in turn is actuated into switch-closing position'by an yoperating lever or finger piece 29 that is pivotally mounted at one end as indicated at 30 andA will bear against'the free end of the springarm 28 `when swung in one direction, vso asv to force the movable contact 2`| into engagement with the fixed contact 26 and close the circuit through the electromagnetic coil 25. This will result in actuation of the resetting rod 22 so as' to push the latter, with a snap action, against garages@ the contact arm I9 which thereby backtc its Vnormal position. i 1

The same switch-operating-A lever oririger piece 29'is utilized for operating the switchfor testing the photoelectric elements and tliefcirL cuit generally. This switch is shown as-com prising a fixed contact' element `3| which-cooperates with a movable' Contact element 32'that is mounted on alspring arm-33 Sothat th'econtacts 3l and 32-are normally engaged in circuitclosing4 position. These two contacts are connectedfin the circuit so thatwhen-theyl arei disengaged to open the circuit,;the operating photoelectric element 6 is thrown out of the circuit, while the balancing photoelectrc element I remains operatively connected-in circuit withv the operating coil 2c of'the electrical responsive device 9. When the main operating cell is thrown out of the circuit, the opposing effect thereof on the balancing cell is eliminated and, consequentvly, said balancing cell will be actuated by the light rays passing through the aperture ll and light tube l2. When the balancing cell so operates, it is indicative that the whole system is in operative condition. Should the cell not operate in this manner, it would be apparent that something Vis wrong in the circuit.

It will be evident that the contact 32 may be moved away from the contact 3l by movement of the operating lever or nger piece 29 against the spring arm 33 in the direction opposite to that in which the finger piece is moved to operate the spring arm 28 of the resetting switch. As shown, the finger piece may conveniently be located between the two spring arms 28 and 33, but other arrangements will occur to those skilled in the art.

It is desirable in some instances to connect a coil 34 of a relay in circuit with `the lamp 23 for operating other devices or signals, e. g. electric gong.

The smoke detector is claimed broadly in copending applications, Serial Number 619,744, led October 2, 1945, Serial Number 74,342, filed February 3, 1949 as a division of Serial Number 604,892, now Patent No. 2,464,211 led July 13, 1945 and owned by a common assignee.

While we have shown our invention as embodied in certain specific details of construction, it should be understood that the construction of the means for permitting smoke to pass through the testing compartment and for preventing light from entering said compartment may be provided within the spirit and scope of the invention.

What we claim is:

l. A smoke detector comprising a casing having a smoke detecting compartment, means for projecting a beam of light through at least a portion of the detecting compartment, light responsive means adapted to be actuated by variations in the light in the detecting compartment, the detecting compartment having a plurality of pairs of apertures in its side walls for admission of uid to be tested for smoke directly from the ambient space around the compartment, each pair of apertures having one aperture positioned above the other so that the circulation of the fluid through the compartment is produced by thermal action, the beam of light producing heat in the detecting compartment for the thermal circulation, and a light obstructing barrier extending transversely of the detecting compartment inwardly from its side walls between each pair of apertures and the light responsive means win te "passed toi prevent practically any rays of exteriorliglitv from entering" through the apertures and, im-l pinging-y upon the light responsive means; the light obstructing barriers the light beam. r

sponsive means adapted to be actuated by variations in the light inthe `detecting compartment, the detecting compartment having a plurality of pairs of apertures in, its side walls for admission of iluid to be tested for smoke directly from theambientspace around the compartment, each pair of apertures having one aperture positioned' above the other so that the circulation of the fluid through the compartmentisv produced by thermal action, the beam of light producingheat in the detecting compartment for i the 'thermal circulation, and a light obstructing apertured partition extending transversely of the detecting compartment inwardly from its side walls between each pair of apertures and the light responsive means to prevent practically any rays of exterior light from entering through the apertures and impinging upon the light responsive means, the apertures in the partitions aligned and having a diameter sufiicient to pass the beam of light.

3. A smoke detector comprising a casing having a smoke detecting compartment, means for projecting a beam of light through at least a lportion of the detecting compartment, light responsive means adapted to be actuated by variations in the light in the detecting compartment, the detecting compartment having a plurality of pairs of apertures in its side walls for admission of the fluid to be tested for smoke directly from the ambient space around the compartment, each pair of apertures having one aperture positioned above the other so that the circulation of the fluid through the compartment is produced by thermal action, the beam of light producing heat in the detecting compartment for the thermal circulation, and a light obstructing tube extending inwardly from the side Wall of the detecting compartment about each of the apertures to prevent practically any rays of light from entering through the apertures and impinging upon the light responsive means, the tubes having a length terminating short oi the light beam.

4. Apparatus for detecting suspended light obstructing matter in a fluid comprising a housing having an elongated compartment formed therein, the compartment having a plurality of pairs of longitudinally spaced apertures in its wall for the passage of fluid through the compartment, a light source adapted to project light rays longitudinally through the compartment, lightresponsive means positioned to receive the light rays, and a plurality of tubes extending inwardly about each of the apertures, each tube eX- tending into the compartment a distance suilicient to block practically all exterior light which may enter through the apertures.

5. Apparatus for detecting suspended light obstructing matter in a fluid comprising a housing having an elongated compartment formed therein, the compartment having a plurality of pairs of longitudinally spaced apertures in its wall for the passage of fluid through the compartment, a light source adapted to project light rays longitudinally through the compartment, lightterminating short of responsive means positioned to receive the light` rays, and a. plurality of tubes extending inwardly about each of the apertures, each tube extending into the compartment a distance suii'lcient to block practically all exterior light which may enter through the apertures, the inner ends of each of the tubes terminating substantially in alignment to permit the passage of light rays from the light source to the light-responsive means.

CLARENCE'4 NOEL CAHUSAC.

DONALD A. DIEHL.

REFERENCES CITED The following references are of record in the 15 file of this patent:

UNITED STATES PATENTS Name Date Number 1- Number a Name Date story, Jr. July 14, 1925 Race Dec. 10. 1929 Freygang Oct. 27, 1931 Sheldon Dec. 1, 1931 Exton Sept. 13, 1932 Simon et al Dec. 5, 1933 Bucknam et al. Aug. 3, 1937 Lyle Dec. 13, 1938 Evans et al. Oct. 13, 1942 Cahusac et al.V Nov. 10, 1942 MacAdams Sept. 9, 194'?` FOREIGN PATENTS Country Date Great Britain July 6, 1933 Great Britain Feb.r 15, 1934 

